I installed my Vortec heads, TES headers, and SDPC TPI base. Stock runners, plenum, TB, cam. Rest of mods in sig.

Before these last round of mods I was maxing out @190 gm/sec.

Now I hit 212 gm/sec@4800 rpm and it still was pulling(haven't gone past 4800 yet). I cross the 190 gm/sec at 4000 rpm, 800 sooner than before.

How significant is this? I assume it is, I am moving more air, therefore fuel through my engine, thus making more power. Does anyone have any formulas or ideas of what kind of power this is?

I will be heading down to the track either today or this weekend, but I just got my car back so this is psyching me up. The car feels strong, but my SOTP dyno isn't that fine tuned. It's also quieter believe it or not. I was expecting it to be a little louder with the headers but it's not.

Overall whatever the results will be I am feeling pretty good about this setup. The car feels bone stock(stock L98 cam, nice idle, good vacuum), just with more power.

My BLMs are 128 +- 4 (except at idle)so that's pretty good. Now I need to get my hands on a wideband for some WOT tuning.

I will also try porting the plenum and running a set of SLP runners in the futur to see if there are any gains. I will also install a set of 1.6 RRs to increase my lift to .443/.459 right in the meat of the Vortecs peak flow!

Sorry for the long post! Lots to talk about

 

Chances are your in PE when you hit 4800 RPm, in which case your correct, you need to get a WB02 to see where you stand as far as AFR.

WHen I did my 350 I saw a very similiar situation as you do. But with the WB, I was still in a very safe arena with AFR, high 11s. This really backed up in my mind just how rich the stock bins must be.

 

What do you mean I am in PE mode at 4800? I don't enter PE mode earlier than that?

I went to the track and noticed that there is a flat spot between 4000-4500 rpm. It might be because I was getting knock and the timing was being pulled back.

How do you make adjustments in PE and AE? what do the values do in those tables?

By the way your track is downhill!!! I just watched your videos.

 

Yes you are in PE mode right off the bat if your WOT off the line. That is what I was alluding to. And the reason I said you need a WB02 to monitor your AFR while also gaging performance.

with the PE vs RPM and coolant you can tweak the WOT AFR to where ever best performance is. You may find that 12.3 is better from 1500-3000 and then 12.7-12.8 for the rest of the RPM.

There is no set AFR I can tell you would be best. Every setup is going to yeild different results. That is why I said a WB and an "accurate" way to determine results is needed.

The flat spot might be from knock, did you scan?

BTW: The track is an NHRA certified track that holds major events through the season. Its NOT downhill, after the track its sloped up a hill since slowdown area is very short. Not sure how the guys going 200 MPH stop to be honest. I know a bunch of people complained. Also that is known as one of the slower tracks in the area.

 

I was just teasing

Actually I am really impressed with your setup.

I am working on getting a WB02 sensor...

I am getting knock along with knock retard, so I think that might be the cause of my flat spot. I am working on figuring out exactly how to pull back my timing for WOT to 31-32 degrees total. Now it seems to be at 35-36, which I beleive is way too much for Vortec heads.

I will do that and try to get back to the track this weekend.

I am also trying to find some shop to build me a custom YPipe. Currently I have the TES headers dumping into my original(modified) ypipe into a beautiful 3" mandrel bent cat back minus the cat. That Ypipe is probably a small restriction.

I will play around with my timing and then start tuning my fuel. I hope to have a WB soon to help out with all this.

By way thanks for the quick response....

Hey why are you on probation?

 

Yeah I knew you were jokin about the track, but yes it does look like that, even in person. Wish I could find a downhill one

Probation: Well do some searching and you will find why. Guess in the nutshell its because I am a bad, bad man

Definately get that knock out of the tune and you will see some nice gains. Sometimes what you will find is its not false knock, so don't panic if you start pulling timing and it doesn't fix the problem. If the addition of gas is also added, and it doesn't help, or its not always present, start looking for sources of rattles, etc.

 

PS: If you liked those videos this is the newest one that a guy put together for me without me knowing as a thankyou. Pretty nice, I also have another version of it, but its huge.

http://temp.corvetteforum.net/c4/ski...s/videost2.wmv

Sorry for the new posting, and not appending it to the last message, but they must turn off the edit mode when your on probabation

 

Hey ski, YOur track IS downhill I have been there!!!!
Just kidding too,llol.
But I wanted to tell you that Mason Dixon Raceway in Maryland
is downhill somwhat and sealevel is about 800 I believe.
But on the bad note its one of the worst tracks I have ever been to. Terrible traction for half of the day, very very mean people, I also drove my car 3 hrs there to find they where only running 1/8 mile (last second decision).

Ohh yeah in case you did not know....
MIR (Maryland Internation Raceway) is less than 100 ft above and I hear a very nice track. Great times come from that track!

 

Ski, with your 350 what maf rate did you max at and at what rpm?

I just got done putting a set of Pro Topline heads and a Stealth Ram on my 355, and previous best with a stock tpi intake was 14.0.... Went to the track tonight and logged a run.

14.1 was the best I could do and my maf maxes out at 253.99 from 4000rpm all the way up to 6000.

Trying to diagnose why the car is so slow. Part of it so far has been determined that after 3200rpm and up my PE spark makes my total spark only 30deg, down from the 38 it was before then.

Would you mind looking at my PE tables? I'm confused with them?

 

Twilight,

There are a few things.....

First the report back from yout ECM will not give you your MAX g/sec accurately after a certain point. It will hang on certain values vs RPM.......

As for the PE, you really need to adjust it per RPM to achieve best performance, and that typically needs a very good way to measure power. dyno or what I prefer, track times, with wb02.

Now from what I have seen on the richer side, small variations in AFR make little difference in power output. clarification from 12.4-12.9 maybe 10hp. Conversly, on the lean side, an equally small change will yield large power changes. Maybe 25+ hp.

I have spent a bunch of time on the dyno this year and last, and countless on the strips playing with these parameters. This is what I have been saying.

More importantly, is the timing. Here very small increments can influence power significantly. My car 2* in either direction, swings power output up to 30-40hp! Here if your at a strip, use the MPH as a tuning tool. My MPH will drop off about 4-6 MPH if I even think of moving mine.

What I did is get it in the area I thought timing, this after having done tons of timing maps and knowing the form they should be in, should be at, ~30*, then increase it 2* via the distributer. writing down the MPH for each run. In a single day you can pinpoint what your timing should be. An eye on the WB is also needed, but like I said before, so long as you are in the 12.x your perfectly safe on your motor, and power output will only vary a little.

Once you hit your max mph, it will start to go the other way, stop and do a chip, with the timing map smoothed out and corresponding to that max timing you have found. If you encounter knock counts on your logging software, it will kill your mPH so that will all be taken into account.

Just go back to your best MPH, and do a chip for that max timing coming in 100% right after your TC lockup point. You will be in good shape and see a huge increase in performance.

This is what worked with my setups and well, while others have their methods, this one is mine. There are a zillion ways to skin a cat, this one is easy and worked multiple times for me.

At Etown my buddy jim with his 383 went from 14s to 12.4 in one day. His builder of the engine screwed up the cam installation and we knew this before that day, but he had a bunch of downtime this summer and wanted to wait till winter to take it back apart. This method worked in a matter of ~4 runs in one afternoon.

Hope this help you out. A millivolt reading from your stock 02 of about 850mv is typically in a safe rich zone. When using these I try to keep it in the 900mv range for added insurance. Since these sensors are less accurate.

So really you have all the tools now in an easy to follow format to get the timing sorted out. Give it a try you will see it works and works well. The only thing that can mess it up is false knock. If the knock reports are not consistent or scattered throughout the logs at non-repeating patterns then you have false knock and it must be addressed before this will work.

I can tell you what I do, but some will hang me for that. So I will leave that off.

Hope this helps...

 

Awesome info! THANKS!